The present invention relates to a three-dimensional wiring board adapted for use in a wiring part of an electrical component or the like and an electric insulating member for the wiring board.
As a known example of a wiring part of a conventional electrical component, there is a printed wiring board that comprises a base, which is formed of a glass fiber cloth impregnated with epoxy resin or the like, and a conductive pattern formed of a copper foil on the base. Since this conventional wiring board lacks in flexibility, it cannot be easily bent into a three-dimensional shape. To obtain the three-dimensional shape, therefore, this wiring board must inevitably be subjected to machining such as skiving. Thus, the degree of freedom of shape is considerably limited, so that the resulting product lacks in versatility.
Another prior art example is a flexible wiring board in which a copper foil for a conductive pattern is formed on a sheet of a synthetic resin such as polyimide. While this flexible wiring board is highly flexible, it requires additional use of a base member, such as a metal frame, to maintain a desired three-dimensional shape. Accordingly, this conventional flexible wiring board is complicated in construction, entailing use of more components. If it is bent with a small bending radius of about 1 mm in a manner such that it is put on the metal base moreover, the polyimide sheet may peel off in some cases. Thus, the conventional wiring board of this type cannot meet the demand for fine bent shapes, either.
Accordingly, the object of the present invention is to provide a high-versatility three-dimensional wiring board, capable of meeting the requirement for small bending radii and easily ensuring a de sired three-dimensional shape, and an electric insulating member used therein.
In order to achieve the above object, three-dimensional wiring board according to the present invention comprises a metal base having a roughed surface subjected to a roughing treatment a d bent into a desired shape, an electric insulating member formed of a polyimide film bonded to the roughed surface of the metal base and serving as an electric insulating layer, and a metal foil, such as a copper oil, bonded to the other surface of the polyimide film and constituting a conductive layer. The roughed surface is a metallic deposit or oxide layer formed on the surface of the metal base, for example.
According to the invention, there may be obtained a high-versatility three-dimensional wiring board, which can be easily worked into and maintain a desired shape without the possibility of its electric insulating layer or conductive layer cracking or peeling off despite its small bending radius. The three-dimensional wiring board according to the invention, which is provided integrally with the metal base, has good heat dissipation properties, and the metal base can serve as a shield for intercepting external magnetic and electric fields.
A method for manufacturing a three-dimensional wiring board according to the invention comprises a roughing treatment process for subjecting a metal base to a roughing treatment, thereby forming a roughed surface, a contact bonding process for attaching a polyimide film to the roughed surface of the metal base and a metal foil by thermocompression bonding, thereby forming a laminate material including the film, base, and foil stacked in layers, and a bending process for forming the laminate material into a desired three-dimensional shape by press molding or the like.
An electric insulating member for a three-dimensional board according to the invention comprises a polyimide film of the heat-bonding type without using adhesive, sandwiched between a metal base having a roughed surface and a metal foil such as a copper foil, one and the other surface sides of the film being in contact with the roughed surface of the metal base and the metal foil, respectively.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.